Process of Extrusion Extrusion Pregelatinized Starch

Process of Extrusion Extrusion Pregelatinized Starch

This is a method of producing pregelatinized starch according to the principle of extrusion extrusion using a screw extrusion extruder. The pre-adjusted wet starch with a water content of 15-20% is added to the extruder, and the starch is rubbed and extruded by the screw shaft to generate heat and gelatinized, and then extruded through high-pressure holes with a diameter of 1-10 mm. The material entering the atmosphere is instantly expanded and dried, and the pregelatinized starch is obtained after crushing and screening. Due to the high shear force, the viscosity of the product decreases, and the solubility of the product is higher than that of the drum method. Since there is basically no need to add water in the manufacturing process, the internal friction heat can be used to maintain the temperature of 120--160 ° C, and no heat source is required for drying.

Drum starch process

Roller method: There are double-roller and single-roller types. The two drums of the double drum dryer move in opposite directions. The starch emulsion is input between the two drums heated to about 150 ° C. The emulsion is immediately gelatinized, dried on its surface into a film, scraped off with a scraper, and crushed. get product. Its quality depends on the degree of gelatinization. By adjusting the concentration of starch milk, the temperature of the drum and the rotation speed, the ability of the product to withstand shearing force, the aging and viscosity during the drying process can be adjusted. The single drum method is to directly transfer the starch milk to the surface of the drum at about 150°C for gelatinization. The single-drum type has low thermal efficiency and small production capacity.

The drum method has the characteristics of continuous production, simple operation, low energy consumption, stable quality and wide application range, but this processing method makes the starch granules rapidly expand to hundreds of times of the original volume The granules are broken, and the product has great defects, including a narrow peak viscosity range, non-integrity granules, can not withstand the shear force and the influence of acid and alkali during use, poor elasticity and fluidity, this method makes starch paste The liquid is only about 80% gelatinized.

Spray starch technology

In a continuous jet cooker, high-pressure steam is mixed with starch milk to gelatinize it, and then spray-dried to make pregelatinized starch.

The characteristic of the spray method is that a hollow spherical particle is obtained without a separate pulverization process. After the starch milk is gelatinized, the viscosity increases sharply, which makes the spraying process complicated and difficult. In addition, the starch milk used has a low concentration, more water needs to be removed during drying, and the temperature of the exhaust gas is high, resulting in high energy consumption and high production costs.